Producing valuable oils from coal tar



Patente d May 23, 1944 PRODUCING VALUABLE OILS FROM COAL TAR Jacquelin E. Harvey, Jr., Washington, D. 0., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia No Drawing. Application June 23, 1942, Serial No. 448,176

4 Claims.

The instant process relates to the production of valuable liquids from mixtures of high temperature coal tar fractions.

More specifically the instant process relates to a method of treating mixtures of high temperature coal tar fractions with a reducing gas (as for instance hydrogen, carbon monoxide or the like) whereby toinduce valuable low boiling liquids, the conditions of the hydrogen treatment being so adjusted as to preclude any substantial polymerization, as for instance, coking.

The term high temperature coal tar as used herein and in the appended claims is meant to identify and include tars resulting from the carbonization of coal at a temperature in excess of 1000 C., as for instance high temperature coke oven tar and gas house tar or the like.

As is known mixtures of high temperature coal tar fractions have a relatively high carbon content as compared to certain other hydrocarbons that are treated with hydrogen or reducing gases.

It is well known in the art to treat mixtures of high temperature coal tar fractions with a reducing gas, as for instance hydrogen or the like, at elevated temperatures and pressures. However, the ill obtains that under certain coordinations of temperature and pressure when hydrogen treating the material named undesirable reactions occurred, as for instance polymerization.

Certain proposals have been brought forth in the hydrogen treating of high temperature coal tar fractions to eliminate or reduce to a minimum polymerizing reactions which are highly undesirable. These proposals consisted of, among other things, employing a pressure in excess of 200 atmospheres when temperatures in excess of 400 C. were used. However, the proposal of coordinating a pressure in excess of 200 atmospheres with a temperature in excess of 400 C. does not entirely solve the problem of pretar fractions may be summarized briefly as follows:

J. G. King, Ph. D., of the British Fuel Research -Board in the Science of Petroleum, Oxford University Press, 1938, page 2156, stated: In view of weight.

apparent that the hydrogenation process must be capableeventually of dealing with high temperature tars or even pitch as well as the more amenable materials such as low temperature tar and tar distillates. In the same reference, page 2163,,Dr. King further states, It' is almost certain, however, that horizontal ,retort and coke oven tars contain a proportion of refractory material which will not, yield to, hydrogenation.

ratio of vapor phase to liquid phase below 8.5 to 1 by weight, as for example below 7.0 to 1 by The following examples set forth-novel means for maintaining the aforenamed liquid and vapor phase relationshipwhen treating .a mixture of high temperature coal tar fractions with hydrogen at temperatures and pressures in excess of 400 C. and 200 atmospheres, respectively.

Example I.A mixture of high temperature coal tar fractions boiling predominantly above 260. C. is passed into a high pressure reaction vessel wherein the feedstock attains a temperature selected between the limits of 375-465" C. The flow of hydrogenis in excess of 8,000 cubic feet per barrel material treated, as for instance 18,000 cubic feet per barrel material treated. The total pressure is 3.00 atmospheres. I The catalyst is tin sulfide and iodoform. The sulfide catalyst may be in comminuted 'form, pelleted, ex-

truded shapes or deposited on suitable carriers.

The proportion of iodoform is-selected between the limits of 0.01-5%, based onthe starting material. The time of treatment is two hours. In the upper portion of the reaction chamber, as for example somewhere above'the middle half, is located a suitably cooled condenser which is maintained at a temperature selected between the limits of 250-425 (3., the selection being so made as to maintain a vapor to liquid phase ratio of less than 8.5 to 1,"that is't'o say, controlling the thevariation in normal tar markets it-will beta material vaporized in the gas stream and removed in vapor form by the gas stream to below about 8.5 by weight.

The reaction chamber is provided with two outlets, one below the other in level so that the liquid phase product may be withdrawn separately from the vapor phase product. The va'- por phase outlet is the upper outlet and thus provides for recovering the vapor phase product (which is vaporized in a stream of hydrogen) without contamination by or from the liquid phase product.

The vapor phase product issues to suitable gas separating and condensing apparatus. Theli'quid phase product with or without releasing pressure may be recycled in admixture with other fresh starting material, if desired, to providefor the production of more or other valuable low boiling oils.

The employment of as catalytic materials a sulfide of a metal'and a halogen derivative gives the greatest percentage conversion known to applicant when compared with other catalytic combinations.

Samples withdrawn from the liquid phase material under treatment at various time stages of the operation will show that reduction of refractory materials, at times including insolubles, is a linear function of the time element, and by tion of below 6 to 1 by weight, that is to say of the materials issuing from the reaction vessel. The vapor phase reaction product is withdrawn from an outlet in the upper portion of the second chamber or zone and sent to suitable gas separating and condensing apparatus. So that the liquid phase product does not contaminate the vapor phase product it is withdrawn from the second reaction Vessel or zone at a level below the vapor phase outlet.

By operating so that the ratio of vapor to liquid phase is below 6 to 1 by weight, the reduction of refractory materials, including insolubles,

' will be found to be a linear function of the time the provision of an extended time of treatment or by recycling operations refractory materials,

and at times insolubles, may be caused to substantially disappear, the while inducing valuable low boiling oils.

Example II Another mode of practicing the process is by employing two distinct temperatures in the reaction operation. As an example, two reaction chambers or zones may be em ployed wherein the temperature in the first reaction chamber or zone is maintainedat between about 405-445 C. and the temperature in the second reaction chamber or zone is more elevated than that employed-in the first stage but not above about 470 0., preferably 465 C.

or somewhat lower whereby to preclude adverse and undesirable-reaction conditions.

-Inthe instance of-employing the-two reaction chambers above named a mixture of high temperature coal tar fractions, as'an example, boiling predominantly above 280 C. is passed to the first reaction-chamber whereina temperature of 410 C. is maintained. The gas fiow is selected below the limits of 25,000 cubic feet per barrel material treated, as for example 20,000 cubic feet or lower but above 8,000 cubic feet. The total pressure is 325 atmospheres. The initial catalyst is molybdenum oxide and a material selected from the group consisting of halogens, halids and derivatives thereof including substitution and addition products thereof. The oxide will in use be changed to a sulfide during operation. A partial pressure of hydrogen sulfide between threequarters and two atmospheres is maintained by addition of sulfur if necessary. At least a portion of the materials under reaction in the first chamber or zone are passedto the second reaction vessel or 'zone' wherein ismaintained a temperature of'about' 455 C. The'totaltime of reaction is in the order of two "and one-quarter hours. p

In the upper section of the second reaction vessel or zone is arranged a condenser whose temperature "is selected between the range of 2 50 -42 5 'C., thetemprature being so selected "as to providea vapor to liquid phase coordin'a- 75 element. Extended periods of treatment will cause the refractory materials, including insolubles, to substantially disappear, or the liquid phase product may be withdrawn from the reaction chamber and recycled and in this manner also the reduction of refractory materials including insolubles becomes a linear function of the time element, the while inducing newly formed low boiling valuable oils.

When using the various mixtures of high temperature coal tar fractions as the starting material under the chosen coordination of time, temperature, pressure and gas flow, a few trials with the condenser temperature chosen between 250-425" C. will readily determine the proper temperature which provides below 8.5 by weight vapor phase to liquid phase ratio.

The pressures employed by the instant process are in excess of 200 atmospheres and are used for the reason that in coordination with the stipulated vapor phase-liquid phase ratio, polymerizing reactions are precluded or held to a minimum.

Gas flows about 8,000 cubic feet per barrel material treated are employed in the instant process for the reason that gas flows selected below that range provide for polymerization. Preferably the flow is in excess of 10,000 cubic feet. When using certain mixtures of high temperature coal tar fractions as the starting material gas flows of 15,000-18,000 cubic feet per barrel material treated provide smooth operation,'however, higher gas flows may be employed as necessityor requirements dictate.

The catalytic materials of the instant process are sulfides of metals and a material selected from the group consisting of halogens, halids or derivatives thereof. Of course, oxides may be initially employed which are subsequently converted to the sulfide in the presence of the sulfur contained in the starting material or as provided by sulfur of extraneous source.

In the instant process a hydrogen sulfide partial pressure of between one-half and three atmospheres is employed-preferably between three quarters and two and one-half atmospheres, as for exampleabout one or one and one-half atmospheres partial pressure, and this may be at least partially maintained by addition of extraneous sulfur containing material.

Based on the starting material the catalyst which is selected from the group consisting of halogens, halids :or derivatives thereof is employed in the percentage of 0.01 to 5%, as'fo'r example between 0.1 and 1.50%.

As an-example of the halogens, halids or *derivatives thereof that may be employed-in con junction with the sulfide or oxide catalystsnlay the limits of about 250-425 C.; preventing the lic chlorides, ammonium chloride, various acids, etc.

At present hydrogen is preferred as the reducing gas but any reducing gas will be operative to a certain extent.

In the combined employment of the catalysts mentioned, many combinations are very effective, as for instance and specifically the sulfides of molybdenum, tin, vanadium, tungsten, uranium and cobalt with specifically iodine or chlorine or their derivatives such as iodoform, hydriodic acid, ammonium chloride, tin chloride, pentachloraphenol and/ or zinc chloride.

The end products of the instant process may be employed as burning oils, motor fuels, diluents, solvents, fungicides or for any other purpose dictated by their composition.

' Various changes may be made within the scope of the appended claims Without departing from the spirit of the invention.

I claim:

1. The process of converting a mixture of high temperature coal tar fractions into lower boiling valuable liquids, which comprises: flowing said material through a reaction chamber wherein is maintained a temperature selected between the limits of about 3'75-465 C., and a pressure in excess of about 200 atmospheres whilst simultaneously flowing through said reaction chamber at least about 10,000 cubic feet of hydrogen-containing gas per barrel feed stock; employingas catalytic materials a sulfide of a metal and a material selected from the group consisting of halogens, halids and derivatives thereof; maintaining a ratio of vapor to liquid phase of below about 8.5 to 1 by weight by cooling at least a portion of the reaction products while yet in the reaction chamber to a temperature below the operating reaction temperature, said lower temperature being selected between the limits of about ZED-425 C.; and preventing contamination of the vapor phase product by the liquid phase product by withdrawing liquid phase products and Vapor phase products from the reaction chamber in separate streams.

2. In a process of converting a mixture of high temperature coal tar fractions into lower boiling valuable liquids, the process which comprises: flowing said material through a reaction chamber wherein is maintained a temperature selected between the limits of about 375-465 C., and a pressure in excess of about 200 atmospheres whilst simultaneously flowing through said reaction chamber in excess of about 10,000 cubic feet of hydrogen containing gas per barrel feed stock; employing as catalytic materials a sulfide of a metal and a material selected from the group consisting of halogens, halids and derivatives thereof while maintaining a hydrogen sulfide partial pressure selected between the limits of about three-quarters to two and one-half atmospheres; maintaining a ratio of vapor to liquid phase of below about 8.5 to l by weight by cooling at least a portion of the reaction products while yet in the reaction chamber to a temperature below the operating reaction temperature, said lower temperature being selected between contamination of the vapor phase product by the liquid phase product by withdrawing liquid phase products and vapor phase products from the reaction chamber in separate streams; and condensing the vapor phase product.

3. The process of converting a mixture of high temperature coal tar fractions into low boiling valuable liquids, which comprises: flowing said material through a high pressure reaction zone maintained at a temperature selected between the limits of about 405-450 C. and a pressure in excess of about 200 atmospheres whilst simultaneously flowing through said reaction zone at least about 10,000 cubic feet of hydrogen containing gas per barrel feed stock; employing as catalytic materials a sulfide of a metal and a material selected from the group consisting of halogens, halids and derivatives thereof; thereafter passing at least a portion of the reaction products through a reaction zone having a more elevated temperature but not in excess of about 470 C.; maintaining in the second reaction zone a ratio of vapor to liquid phase of below about 8.5 to 1 by weight by cooling at least a portion of the reaction products while yet in the second reaction zone to a temperature below the operating reaction temperature, said lower temperature being selected between the limits of about 250--4=25 C.; and preventing contamination of the vapor phase product by the liquid phase product by withdrawing vapor phase products and liquid phase products from the reaction chamber in separate streams.

4. The :process of converting a mixture of high temperature coal tar fractions into low boiling valuable liquids, which comprises: flowing said material through a high pressure reaction zone maintained at a temperature selected between the limits of about 405-450 C. and a pressure in excess of about 200 atmospheres whilst simultaneously flowing through said reaction zone in excess of about 10,000 cubic feet of hydrogen containing gas per barrel feed stock; employing as catalytic materials a sulfide of a metal and a material selected from the group consisting of halogens, halids and derivatives thereof while maintaining a hydrogen sulfide partial pressure selected between the limits of three-quarters to two and one-half atmospheres; thereafter passing at least a portion of the reaction products to a reaction zone having a more elevated temperature but not in excess of about 470 C.; maintaining in the second reaction zone a ratio of vapor to liquid phase of below about 8.5 to l by weight by cooling at least a portion of the reaction products while yet in the second reaction 7 zone to a temperature below the operating reaction temperature, said lower temperature being selected between the limits of about 250-425 C.; preventing contamination of the vapor phase product by the liquid phase product by withdrawing vapor phase products and liquid phase products from the reaction chamber in separate streams; and condensing the vapor phase product.

JACQUELIN E. HARVEY, JR.

CERTIFICATE or CORRECTION. Patent No. 2,5u9,721. May 2;, 19m.

JACQUELIN E. HARVEY, JR.

ertified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, sec- "about" read -above-; and that the said Letters orrection therein that the same may con- It is hereby 0 mi col'umn, line 58, for

Patent should be read with this 0 f the case in the Patent Office.

Leslie Frazer form to the record 0 Signed and sealed this 8th day of August,

(Seal) Acting Commissioner of Patents. 

